Grinder



July 13, 1948. L. o. FRENCH 2,445,138

GRINDER I Filed Nov. 1a, 1946 '2 Sheets-Sheet 2 awn/r012.-

Patented July 13, 1948 UNITED- STATES PATENT OFFICE GRINDER FrenchjMilwaukee, Wis- Application November 13, 1946, Serial No. 710,791

6-Claims.

The invention relates to'grinders and more -particularly to so-called lathe or tool post grinders for use on lathes, milling machines, shaper's', grinding machines, and othermachine'tools. Grinders of the :above type usually'embodya constant speed electric motor and vary thespeed of the wheel spindle by interchangeable beltconnected pulleys on the motor shaftand wheel spindle. Constant changing of belt pulleys for different kinds of work is a'decided-inconvene ience, and the pulley :hubs wearfrom frequent changing, so that-theycannot be tightened up securely and have to be replaced. One of the objects of this invention is to provide a portable grinding tool in which the motor shaft and wheel spindle shaft have'a constant drive ratio connection with each other to increase the'speed of the wheel spindle over that of the -motor and in which all the speed changes for the wheel spindle are varied by varying the motor speed through a wide range by the manual adjustment of a con'-' tinuously variable speed governor for'themotor. With such an arrangement no time is lost in adjusting the grinder as it is always-ready for the internal grinding of small holes or the ex-' ternal grinding of large diameter work and at a speed best suited for each particular job.

Another object of the invention is to eliminate the usual belt by providing a constant ratio friction drive in which one of the wheels, preferably that on the motor shaft is provided with a somewhat compressible friction drive surface which is brought into efficient pressure driving engagement with a metal wheel on' the wheel spindle shaft by the bodily movement or turning of the wheel spindle in a path eccentric-to its supporting mounting and the locking of the spindle quill to the frame of the machine when the proper driving pressure connection is made.

' A further object of the invention is to provide an improved arrangement for adjustably securing the wheel spindle supporting means in any desired circumferential adjustment relative to the motor shaft through a wide range. "More particularly, the wheel spindle quill is mounted in bearing bosses formed on a pair of bands that surround parts of the motor housing and locking means preferably a quick acting lever lock or looks are used to clamp said bands to'said housing in any desired angular position of the wheel spindle relative to the motor shaft, so that the grinding wheel may be quickly set at the desired height relative to the machine on which is used to properly contact the work.

The invention further consists in the several (01. sr-zss) i'frf features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

Inthe drawings: 1

I Fig. l is a side elevation view of a grinder embodying the invention;

Fig. 2 is a plan view of the grinder, parts beingthe speed'is slowest. Thus when a, heavy-load is thrown on a universal or series motor, the speed decreases, with the result of a great gain in torque, to take care of the increased load, and

when such. a motor is used in a grinder of the type herein described, the larger wheels whichv require greater torque at lower speeds maybe efficiently. operated if speed governing mechanism be used which will permit the motor to exercise its. torque changing characteristics most efli,-- ciently. I believe the association of a motor of, this type as hereinafter described is new and is of considerable advantage as it eliminates manyparts and several operations necessary with the known practice in devices of this kind of using a constant speed motor and interchangeable pulleys and belt connections for varying the speed of the wheel spindle. The governor control for in; t t r maybe'of any suitableconstruction,

and in this connection reference is made to U. S. Patent No. 1,767,146, of June 24, 1930, to Royal Lee. .In the patent above referred to there is n disclosed an electric motor whose shaft operates 'a centrifugally operable speed control governor whose speed range is settable by a manually operable member, the governor including a switch in the motor circuit, which when the speed of the motor reaches a value at which the governor 50v is set, opens so that the set speed is not materially exceeded. A governor mechanism o f this kind may be used to operate in ranges of 1000 to 10,-000 R. P. M. or from 2500 to 15,000 R. P. for example, and through the manual setting of the governor the speed of the motor is contin- Fig. 4 is a detailed vertical sectional view taken Motors of the type just men-. tioned have:the characteristic that the torqueture shaft [2 and carrying collector rings 13 and. i.

M which are operatively connected, as shown in said patent, to one of the motor field Windin'gs and the armature. A spring supported contact, I5 is mounted on the disk H and connected "to the ring l3, and a similar contact l6 iis mountedr on said disk and connected to the ring 14. The

mounting of the contacts l5 and [6 are" ata' distance from the center of the disk II, and as the motoror-armature' shaft l2 revolves, the con: tacts l 5 and-=|Iirnove outwardly under the action of centrifugal force. The contact 5 "may' move outwardly to the extentdefined' by a stop pin l'l.

The contact 16 may also move outwardlfi'but' the extent of" its outward-"movement is determined-by the operator throughits connection by a link I 8* with one arm of-"a bellcrank lever l9 pivotally mounted on the disk! I the other arm I 9""of said "-le'verbeing "engaged by a manually settable pin ZO of insulating material; 1 Thus de pending upon the position of the pin will depend the amount that the-contact"!6*moves'outwardly and consequently the speedof the motor shaft I2 at which the contacts l5 'and l6 's I rate," so that the load circuit oi' th'emotor is opened, so that the set speed is not materially" exceeded- As*-herein shown, the "manually settable=-'means-"includesa screw 2| carrying the pin 20-and working'ima m'anually rotatable nut- 22 pinned-tea manually settable knob 23 whichis mounted 'on a sleeve support 24"secured 'by=a' nut" 25"*-to=-th'e end cap" not the motor'housing-s A pin zrcmnc support '24forms a keyworkingin a key slot 28 "the-screw 2 l so that as the-knob 23 "istur-ned; the 'screw2 I will be moved le'ngth Wise relative to the bell crank 'lever'l 9, -an'd-thus= move 1 the pin 2ll--either"inwar dly or permit 'its outward movement under the: action of forces acting'jonj-"said pin throughsaid -1ever I9. The knob 23' has a pointer orindex member '25 00-' operating with 'a dial13D provided-with speed index designations indicated by the lines 3| in' "Fig.3; so that the knob 23 maybeturned-tobring the: pointer29 into line with-any desired speed indication" within '1 the range of the" governor." Thus thei'speed' 'oftheshaft'fl may be varied througha wi'derang'e"ofspeedi;

With a speed vernor ofjthe circuit closure tYpethe 'full'current ofithe motoris alwaysand' instantly,availableunder the demand of .the mo-.. tor itself. and associated with a universal orseries... motor the larger wheels can be operated efli'cient 1yjatlowspeedbecause .of the increase in torque a1-,-,1o"w..speeds.v The-@circuit .closure type of governorlthns has -distinct advantagesv over. a rheostat :orivariableresistance control becausesuch a= control,-as..a speed. control, acts tocut. downthe 1 current .vavailable. to .the motor at lower. speeds and thuscannotefliciently drive the largergrind er .iwheelslat thetlower -.-speeds.required.

A! grinder'quill supporting frame is formed by:- awpaimotmetalbands 32 which have a close fit upon.v the..cap.- -portions :26-iand 33 '-of--the..motorhousing and turn about the shaft 12 as a center, each cap having an annular flange 34 cooperating with an annular flange 35 on the main body 36 of the housing to hold said bands against lengthwise movement relative to said housing. The bands 32 may be connected together by a bridge piece, if desired. Each band is provided with a bearing boss 31 in which the wheel spindle 38, mounted in the quill 39, is eccentrically mounted. As herein shownzthe spindlef' 38 has an eccentric mounting in-the "quill 391" The quill 39-may be 01 any standard or known construction in which the wheel spindle 38 is mounted either in preloaded ball bearing journals or in journals formed ,of tungsten carbide, and wick oilers are provided tri'city relativerto thewpivot lzfacti-ng-asia wedge between z-th'e :boss and'theizquiII ;to firmly bindth'e quill to saidtb oss, the: surfaceriof-t said fcamportion preferablysibeingiforme'd fon a :radius as shown in" Fig. 5 substantially-the same'ras that part of the quill lwhich' itfien'gages, so thahi no sharp' edges actv tou dig nto or'"roughenthe external surface of the" quills l.

Forfclanipingith bands-3% in any. desired position' of circumferential"l adjustment" relative" to the m'otonhousin-g; so thatithe grinder-wheel 46- on the- -spind-le 38' 'may besdispes'ecb in :proper relation'to the rworkxeach: band i rovided 'with" a slot 41 =positi0neda'ationersidefof the bcaring boss 31::in rwhicha icam' type" locking: 's1ever-"48-' simi1ar; to'ithe =lever =43' is =pivotal'ly' mounted" on a bolt 43 mounted'n'n zthe'wal'ls :o'f "sai'dttboss-g' the; slot 41 'at" its"centralmportion:rextending-=through the band, similanto the slot 'lllyrso that 'th'e face 1 of l the cam portion of 'Fsaid; clever? M3 tmays be brought into wedging engagementawith the end" caps of "the housing ion-i which said ba-nds are mounted -to' firmly-clampzz'@thewbandseto said imotor :housingc Where the 'i-bands are connected together by the bridge :piece;previously referre'dwto; a single lever simila-n-to': the lever Asa-mounted ran-said ibridge piece mayacocperatevwith:the housing to lock the bands againstturning-movementfi A-constant speed .ratio driving lconnection between the-"11101391? shait" I 2 -and the "wheelspindle 384s 1p1 0vided -so-that the .wheelspind-Ieis driven at a higher speed thanrthe-motor-shaft,inmost cases-atleast twice'asrast as said-shaft. Preferably for motors :having iaxgoverned: speedrange between one thousandand-.ten thousandrevolu-'- tions per 1-minute;v thissratio ris pne to 4 four, and

per .minute which'rspeed: range will :accommodate the use ":of' large wheels sofa three to five inches inidiameter for. external grinding down-to mounted Wheels-of one eighth .inch in--. diameter.

onthe-motor shaft connectedby a belt to-a: pulley This Y fixed ratio drivingnconneetionmay@be a pulley.

on thewheel spindle, but in orderato-vget away from the troubles sometimes encountered with a belt.drive;=I-provide a direct friction wheel drive connection between the shafts I2 and 738.

The direct friction drive wheel connection ineludes a; metal lwheel 5!!1 mounted on.- the wheel spindle 38 and a wheel 5| mounted on the motor shaft-12 and having a somewhat compressible driving rim portion 52 which may be mounted on a metal nmerrmg '53 "secured to'" the body of the. wheel by clamping saidrim 53 between a back plate 54 integral with the hub of said wheel 5| and a detachable front plate 55 secured in position by a nut55' on the motor shaft |2,the plates 54 and55 having annular grooves 51 receiving.v

tions or cords molded therein.- The metal wheel 50 'maybe'of. cast iron or suitable aluminum or magnesium alloy. Friction drives :requireapressure'connection between the wheels involving a bodily movement of one of the shafts l2 or 38 toward each other. In the present instance the spindle 38 having an eccentric mounting in the bosses 3! of the bands 32 turning of the spindle quill 39 will act to change the radial position of the spindle 38 relative to the shaft l2, so that said spindle can be moved inwardly toward said shaft and thus bring the wheels 50 and 5| into -pressure driving engagement with each other,

the spindle 38 is brought and secured in efficient fixed ratio driving relation with the motor shaft l2, .and this is preferably accomplished when the bands 32 are in their desired position of circumferential adjustment.

Thus the only operations in most instances that need to be performed by the operator in setting up the grinder for its Work are the setting of the knob 23 to the desired speed position and the attachment of a grinding wheel 46 to the spindle 38 since the adjustment of the height of the spindle relative to the machine on which the grinder is used to bring it into axial alinement with the axis of the work is usually made but once or very infrequently and the wheels 50 and 5| once properly adjusted in driving engagement need no further attention.

For mounting the grinder on a machine tool, the motor may have a supporting base portion 60 formed integral with or operatively connected to it, said base portion having a base plate 6| secured thereto and carrying an adjustable clamping bolt member 62 for engaging in the ways of a tool post slide, a table or other support to clamp the base 60 thereto.

Where in grinders of this general type the wheel spindle is not circumferentially adjustable relative to the motor housing but is vertically adjustable relative to the supporting base, then the bearing bosses 31 shown herein may be formed in the present instance as an integral part ofthe.

housing caps 26 and 33.

-I desireit'to be understood that'this invention is not to'be' limited to any particular form or arrangement of parts except in so far as such'limitations are-included in the claims.

-What I claim as my invention is:

1. ma grinding machine of the type described,

the combination of a support, an electric motor having a shaft and a grinder quill having a spindle carried by said support, a constant ratio dircct friction'pressure drive connection between a wheel on said motor shaft and a wheel on said :spindleto drive said spindle at a speed greater than that of said motor shaft, means including a lever and-an eccentric mounting connection for the spindle formov-ing the same relative to'said motorshaft to establish a pressure drive connectiombetweensaid wheels, pivoted cam lever lock- I in ymeans.for securing said quill and spindle in adjusted position, a variable motor speed gov ernorzdriven by said motor shaft, and manually sett-able means for the governor for varying the governed speed of said spindle.

2.;Ina grinding machine of the type described, the combination of a support, an electric motor carried by said support and having a shaft and a housing with spaced annular grooves, a pair of metal bands surrounding said housing and mounted for turning in said grooves and provided with bosses, a grinder quill mounted in said bosses and having a wheel spindle, a driving connection between said motor shaft and wheel spindle, and

pivoted cam lever locking means for clamping said bands to said motor housing to secure said quill in the desired circumferential position relative to said housing.

3. In a grinding machine of the type described, the combination of a support, an electric motor carried by said support and h'aving a shaft and a housing with spaced annular grooves, a pair of metal bands surrounding said housing and mounted for turning in said grooves and provided with bosses, a grinder quill mounted in said bosses and having a wheel spindle, a driving connection between said motor shaft and wheel spindle, a pivoted cam lever mounted on each band and engageable with said housing to clamp the band to said housing to secure said quill in the desired circumferential position relative to said housing.

4. In a grinding machine of the type described, the combination of a support, an electric motor carried by said support and having a sh'aft, a grinder quill having a wheel spindle eccentrically mounted therein, supporting means for said quill, a driving connection between said motor shaft and said wheel spindle effective on the adjustment of said quill in said supporting means, and pivoted cam lever locking means on the supporting means for the quill for fixing said quill against movement to maintain the adjustment of said driving connection.

5. A grinding unit consisting of a base support, an electric motor of the series type carried by said support and having an armature shaft extended to form a drive shaft, a quill carried by said support and having a spindle parallel to said armature shaft, a grinding wheel on one end of said spindle, a friction wheel on the other end of said spindle, a friction wheel on said drive shaft in direct friction pressure drive connection with the friction wheel on said spindle to drive said spindle, means for moving said spindle relative to said armature shaft to effect said drive connection,

7 means'ior maintaining: saidconneotiong and :a variable motor speed governor on. said motor; said governor including a.switc11' in the: motor". circuituresponsive to the speed i of said motor to maintain its speed substantially constant undervarying: demands vplaced upon it by the sgrinding Wheel, and manuallYsettable means .for-uthegova t ernor for varying the governed speed of-saida-motor-:to,.-vary the speed-of said. spindle-for varying diameters of grinding wheels. 10:1,

fizwA grinding unit'consisting of :a base support ameleotric motor of the series type carried bysaid support'and havin an armatureshaftextended-- toyform a drive shaft,- a quill carriedbysaid support and havinga spindle paralleizto said armamxNumber,

ture'sh'a'ft, a grinding Wheel on oneiendof saidspindle,a friction Wheel von the other: end of said spindle, a friction Wheel on; said drive .shaft in:- directifriction pressure drive connection .withwthe friotiomwheel on saidspindle to ,drive-saidz'spin- 2%, 23392714,.

die. at'za speed greater than that of saiddrive shaft; means for moving said-spindle relativeto: said-armature shaft'to efiect said drive-connec tion; means-for maintaining said connection, and

a variable motor speed-governor on said"mot0r,u 150795331:

said igovernor including va switch in the motor-nir- 8:; cuitiresponsiveeto: the speed not i said? --moto1-=-, tot.- maintain its speed.- substantiallyconstant: linden varying-demands;eplaced :uponiitby, the: grinding wheel, and-manuallynsettable means. for, the-gov t ernoriforwaryingmhe "governednspeed of isaidi moton-towary the speed of v said spindleforr varying. diameters of grinding-zrwheels.-

LOUIS-0. FRENCH;

REFERENCES cIT n- The following references are of reoordin the file of this patent:

UNITED :STATES PATENTS 

